U.S. patent application number 15/928253 was filed with the patent office on 2018-09-27 for system and method for determining location information for a mobile radio transmitter.
The applicant listed for this patent is LEGIC Identsystems AG. Invention is credited to Thomas KNOBLAUCH.
Application Number | 20180279253 15/928253 |
Document ID | / |
Family ID | 58412821 |
Filed Date | 2018-09-27 |
United States Patent
Application |
20180279253 |
Kind Code |
A1 |
KNOBLAUCH; Thomas |
September 27, 2018 |
SYSTEM AND METHOD FOR DETERMINING LOCATION INFORMATION FOR A MOBILE
RADIO TRANSMITTER
Abstract
A positioning system (10) for determining location information
of/for a mobile radio transmitter (1) comprises an antenna system
(2) which includes a plurality of antennas (21) aimed at different
directions and arranged on one common antenna carrier (20). The
positioning system (10) comprises a receiver system (3)
electrically connected to the antennas (21) and configured to
receive via each of the antennas (21) a radio signal (7)
transmitted by the mobile radio transmitter (1). The positioning
system (10) further comprises a processing circuit (4) electrically
connected to the receiver system (3) and configured to calculate
the location information of/for the mobile radio transmitter (1)
based on the radio signal received at each of the antennas (21).
The location information includes at least angular direction of the
mobile radio transmitter (1) with respect to the antenna system
(2).
Inventors: |
KNOBLAUCH; Thomas; (Jona,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LEGIC Identsystems AG |
Wetzikon |
|
CH |
|
|
Family ID: |
58412821 |
Appl. No.: |
15/928253 |
Filed: |
March 22, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 7/08 20130101; H04W
64/00 20130101; G01S 5/0221 20130101; G01S 5/12 20130101; H04W
64/006 20130101; H04B 17/318 20150115; G01S 3/043 20130101; G01S
19/37 20130101; G01S 11/06 20130101; H04B 7/02 20130101; G01S 5/02
20130101; G01S 5/0054 20130101; G01S 3/28 20130101 |
International
Class: |
H04W 64/00 20060101
H04W064/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2017 |
CH |
00381/17 |
Claims
1. A positioning system for determining location information for a
mobile radio transmitter, the system comprising: an antenna system
comprising a plurality of antennas aimed at different directions
and arranged on one common antenna carrier; a receiver system
electrically connected to the antennas and configured to receive
via each of the antennas a radio signal transmitted by the mobile
radio transmitter; and a processing circuit electrically connected
to the receiver system and configured to calculate the location
information for the mobile radio transmitter based on the radio
signal received at each of the antennas, the location information
including at least angular direction of the mobile radio
transmitter with respect to the antenna system.
2. The positioning system of claim 1, wherein the receiver system
is further configured to determine received signal strengths of the
radio signal received at each of the antennas; and the processing
circuit is further configured to calculate and include in the
location information a distance of the mobile radio transmitter
from the antenna system, using the received signal strengths of the
radio signal received at each of the antennas and radio
transmission characteristics of the mobile radio transmitter.
3. The positioning system of claim 2, wherein the receiver system
is further configured to extract from the radio signal orientation
data which indicates a current spatial orientation of the mobile
radio transmitter; and the processing circuit is further configured
to calculate the location information for the mobile radio
transmitter, using the received signal strengths of the radio
signal received at each of the antennas, the current spatial
orientation of the mobile radio transmitter, and the radio
transmission characteristics of the mobile radio transmitter.
4. The positioning system of claim 2, wherein the receiver system
is further configured to extract from the radio signal orientation
data which indicates spatial orientation of the mobile radio
transmitter; and the processing circuit is further configured to
determine the radio transmission characteristics of the mobile
radio transmitter using the received signal strengths of the radio
signal received at various spatial orientations of the mobile radio
transmitter, and to store the radio transmission characteristics
for the mobile radio transmitter.
5. The positioning system of claim 2, wherein the receiver system
is further configured to extract from the radio signal a device
type of the mobile radio transmitter; and the processing circuit is
further configured to determine the radio transmission
characteristics of the mobile radio transmitter from a data store
using the device type of the mobile radio transmitter.
6. The positioning system of claim 1, wherein the receiver system
is further configured to determine propagation times of the radio
signal received from the mobile radio transmitter at each of the
antennas; and the processing circuit is further configured to
calculate a distance of the mobile radio transmitter from the
antenna system using the propagation times determined at each of
the antennas.
7. The positioning system of claim 1, wherein the processing
circuit is further configured to calculate based on the radio
signal received at each of the antennas at least one of: a
two-dimensional location of the mobile radio transmitter and a
three-dimensional location of the mobile radio transmitter.
8. The positioning system of claim 1, wherein the processing
circuit is further configured to determine and store a movement
path, including movement direction, of the mobile radio transmitter
based on the location information calculated for the mobile radio
transmitter, and to use the movement path of the mobile radio
transmitter to calculate the location information for the mobile
radio transmitter.
9. The positioning system of claim 1, wherein the receiver system
is further configured to determine frequency shift of the radio
signal received from the mobile radio transmitter; and the
processing circuit is further configured to determine a direction
of movement of the mobile radio transmitter.
10. The positioning system of claim 1, wherein the processing
circuit is further configured to determine whether the mobile radio
transmitter is located in front of or behind an access control
device.
11. The positioning system of claim 1, wherein the processing
circuit is further configured to determine whether the mobile radio
transmitter is located in front of or behind another mobile radio
transmitter with respect to an access control device.
12. The positioning system of claim 1, wherein at least some of the
antennas have spatial directivity.
13. The positioning system of claim 1, wherein the antenna system
comprises three or more antennas in a triangular arrangement.
14. The positioning system of claim 1, wherein the antenna system
comprises two antennas in a parallel or antiparallel
arrangement.
15. The positioning system of claim 1, wherein the antenna system
and the receiver system are configured to receive radio signals
transmitted by a mobile radio transmitter of at least one of: a
wireless local area network, a Bluetooth transceiver, and a Zigbee
transceiver.
16. The positioning system of claim 1, wherein the processing
circuit is configured to calculate the angular direction of the
mobile radio transmitter with respect to the antenna system by
determining a sector in which the mobile radio transmitter is
located with respect to the antenna system, using minimum and/or
maximum signal strengths of the radio signal received at each of
the antennas; and calculating the angular direction of the mobile
radio transmitter with respect to the antenna system, using the
signal strengths of the radio signal received at the antennas
located in the sector.
17. A method of determining location information for a mobile radio
transmitter, the method comprising: arranging a plurality of
antennas on one common antenna carrier and aimed at different
directions; receiving by a receiver system via each of the antennas
a radio signal transmitted by the mobile radio transmitter;
calculating by a processing circuit the location information for
the mobile radio transmitter based on the radio signal received at
each of the antennas, the location information including at least
angular direction of the mobile radio transmitter with respect to
the antenna system.
18. The method of claim 17, wherein the method further comprises
the receiver system determining received signal strengths of the
radio signal received at each of the antennas; and the processing
circuit calculating a distance of the mobile radio transmitter from
the antenna system, using the received signal strengths of the
radio signal received at each of the antennas and radio
transmission characteristics of the mobile radio transmitter.
19. The method of claim 17, wherein the method further comprises
the receiver system determining propagation times of the radio
signal received from the mobile radio transmitter at each of the
antennas; and the processing circuit calculating a distance of the
mobile radio transmitter from the antenna system using the
propagation times determined at each of the antennas.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a positioning system and a
method for determining location information for a mobile radio
transmitter.
BACKGROUND OF THE INVENTION
[0002] The satellite based Global Positioning System (GPS) provides
useful location information for devices that are equipped with
respective GPS receivers. The publicly accessible GPS provides
location information that is accurate enough for locating a device
and its bearer within a range of a few meters. The actual accuracy
users attain depends on various factors, including atmospheric
effects, sky blockage, receiver quality, etc. While an accuracy of
say two to three or four meters is an impressive achievement, it is
not sufficient for discriminatory applications requiring "local
area positioning" where two or more devices within close proximity
to each other need to be identifiable and discernible on the basis
of their location. Examples of such applications include wireless
payment at a payment terminal, where individuals in a line up or at
neighboring terminals need to be distinguished, or access control
based on wireless access token systems, where individuals in front
or behind an access control device, such as a door or a gate, need
to be distinguished.
[0003] US 2011/205969 describes a location system which includes a
plurality of beacon transmitters each positioned at a respective
location. Each beacon transmitter includes a plurality of antennas
positioned in a circular arrangement. Each beacon transmitter is
configured to transmit an identification signal having a plurality
of reference data and to transmit a directional signal from the
plurality of antennas by selecting one of the antennas at a time in
sequence around the circular arrangement to simulate a rotating
antenna. The location system further includes a receiver configured
to receive the identification signals and a plurality of
Doppler-shifted directional signals each corresponding to one of
the directional signals, wherein the receiver is configured to
generate a plurality of time data for each received Doppler-shifted
directional signal, and wherein the receiver is configured to
determine a location of the receiver using each Doppler-shifted
directional signal, each time data, and each identification signal
received from the plurality of beacon transmitters.
[0004] WO 2016/000121 describes a multiple-layer beacon sweeping
method performed by an access node and user equipment. The method
comprises at least a first beacon sweeping with a first set of
beams and a first coverage area and a second beacon sweeping with a
second set of beams and a second coverage area, whereby the first
coverage area is larger than the second coverage area.
[0005] CN 102170697 describes an indoor positioning method which
acquires the signal strength transmitted by a plurality of beacon
nodes received by a terminal to be positioned.
SUMMARY OF THE INVENTION
[0006] It is an object of this invention to provide a positioning
system and a method for determining location information for a
mobile radio transmitter. In particular, it is an object of the
present invention to provide a system and a method for determining
the location of a mobile radio transmitter, without the need for
multiple satellites or beacon systems. More particularly, it is an
object of the present invention to provide a system and a method
for determining the location of mobile radio transmitters such that
the mobile radio transmitters can be discerned from each other even
when they are in close proximity to each other, within one or two
meters, without the need for multiple satellites or beacon
systems.
[0007] According to the present invention, at least some of these
objects are achieved through the features of the independent
claims. In addition, further advantageous embodiments follow from
the dependent claims and the description.
[0008] According to the present invention, at least some of the
above-mentioned objects are achieved in that a positioning system,
for determining location information for a mobile radio
transmitter, comprises an antenna system with a plurality of
antennas aimed at different directions and arranged on one common
antenna carrier. The positioning system further comprises a
receiver system electrically connected to the antennas and
configured to receive via each of the antennas a radio signal
transmitted by the mobile radio transmitter. The positioning system
further comprises a processing circuit electrically connected to
the receiver system and configured to calculate the location
information for the mobile radio transmitter based on the radio
signal received at each of the antennas. The location information
includes at least the angular direction of the mobile radio
transmitter with respect to the antenna system.
[0009] In an embodiment, the receiver system is further configured
to determine received signal strengths of the radio signal received
at each of the antennas. The processing circuit is further
configured to calculate and include in the location information a
distance of the mobile radio transmitter from the antenna system,
using the received signal strengths of the radio signal received at
each of the antennas and radio transmission characteristics of the
mobile radio transmitter.
[0010] In a further embodiment, the receiver system is further
configured to extract from the radio signal orientation data which
indicates a current spatial orientation of the mobile radio
transmitter. The processing circuit is further configured to
calculate the location information for the mobile radio
transmitter, using the received signal strengths of the radio
signal received at each of the antennas, the current spatial
orientation of the mobile radio transmitter, and the radio
transmission characteristics of the mobile radio transmitter.
[0011] In an embodiment, the receiver system is further configured
to extract from the radio signal orientation data which indicates
spatial orientation of the mobile radio transmitter. The processing
circuit is further configured to determine the radio transmission
characteristics of the mobile radio transmitter using the received
signal strengths of the radio signal received at various spatial
orientations of the mobile radio transmitter, and to store the
radio transmission characteristics for the mobile radio
transmitter.
[0012] In a further embodiment, the receiver system is further
configured to extract from the radio signal a device type of the
mobile radio transmitter. The processing circuit is further
configured to determine the radio transmission characteristics of
the mobile radio transmitter from a data store using the device
type of the mobile radio transmitter.
[0013] In an embodiment, the receiver system is further configured
to determine propagation times of the radio signal received from
the mobile radio transmitter at each of the antennas. The
processing circuit is further configured to calculate a distance of
the mobile radio transmitter from the antenna system using the
propagation times determined at each of the antennas.
[0014] In a further embodiment, the processing circuit is further
configured to calculate based on the radio signal received at each
of the antennas a two-dimensional location of the mobile radio
transmitter and/or a three-dimensional location of the mobile radio
transmitter.
[0015] In an embodiment, the processing circuit is further
configured to determine and store a movement path, including
movement direction (and speed), of the mobile radio transmitter
based on the location information calculated for the mobile radio
transmitter, and to use the movement path of the mobile radio
transmitter to calculate the location information for the mobile
radio transmitter.
[0016] In a further embodiment, the receiver system is further
configured to determine frequency shift of the radio signal
received from the mobile radio transmitter. The processing circuit
is further configured to determine a direction (and speed) of
movement of the mobile radio transmitter.
[0017] In an embodiment, the processing circuit is further
configured to determine whether the mobile radio transmitter is
located in front of or behind an access control device.
[0018] In a further embodiment, the processing circuit is further
configured to determine whether the mobile radio transmitter is
located in front of or behind another mobile radio transmitter with
respect to an access control device.
[0019] In an embodiment, at least some of the antennas have spatial
directivity.
[0020] In a further embodiment, the antenna system comprises three
or more antennas in a triangular arrangement.
[0021] In an embodiment, the antenna system comprises two antennas
in a parallel or antiparallel arrangement.
[0022] In a further embodiment, the antenna system and the receiver
system are configured to receive radio signals transmitted by a
mobile radio transmitter of a wireless local area network, a
Bluetooth transceiver, and/or a Zigbee transceiver.
[0023] In an embodiment, the processing circuit is configured to
calculate the angular direction of the mobile radio transmitter
with respect to the antenna system by determining a sector in which
the mobile radio transmitter is located with respect to the antenna
system, using minimum and/or maximum signal strengths of the radio
signal received at each of the antennas; and calculating the
angular direction of the mobile radio transmitter with respect to
the antenna system, using the signal strengths of the radio signal
received at the antennas located (at least partially) in the
determined sector.
[0024] In addition to the positioning system, the present invention
also relates to a method of determining location information for a
mobile radio transmitter. The method comprises arranging a
plurality of antennas on one common antenna carrier and aimed at
different directions; receiving by a receiver system via each of
the antennas a radio signal transmitted by the mobile radio
transmitter; calculating by a processing circuit the location
information for the mobile radio transmitter based on the radio
signal received at each of the antennas, the location information
including at least angular direction of the mobile radio
transmitter with respect to the antenna system.
[0025] In an embodiment, the method further comprises the receiver
system determining received signal strengths of the radio signal
received at each of the antennas; and the processing circuit
calculating a distance of the mobile radio transmitter from the
antenna system, using the received signal strengths of the radio
signal received at each of the antennas and radio transmission
characteristics of the mobile radio transmitter.
[0026] In a further embodiment, the method further comprises the
receiver system determining propagation times of the radio signal
received from the mobile radio transmitter at each of the antennas;
and the processing circuit calculating a distance of the mobile
radio transmitter from the antenna system using the propagation
times determined at each of the antennas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The present invention will be explained in more detail, by
way of example, with reference to the drawings in which:
[0028] FIG. 1: shows a block diagram illustrating schematically a
positioning system for determining location information for a
mobile radio transmitter.
[0029] FIG. 2: shows a block diagram illustrating schematically
angular direction and distance of a mobile radio transmitter with
respect to an antenna system of a positioning system.
[0030] FIG. 3: shows a block diagram illustrating schematically a
top view of an antenna system with a triangular arrangement of
three antennas aimed at different directions, the axes of direction
running in a common plane, enabling 2D positioning.
[0031] FIG. 4: shows a perspective diagram illustrating
schematically an antenna system with several antennas aimed at
different directions where the axes of direction do not run in one
common plane, enabling 3D positioning.
[0032] FIG. 5: shows a block diagram illustrating schematically a
top view of an antenna system with antiparallel arrangement of two
antennas having separate electrical grounds.
[0033] FIG. 6: shows a block diagram illustrating schematically a
top view of an antenna system with antiparallel arrangement of two
antennas sharing a common electrical ground.
[0034] FIG. 7: shows a flow diagram illustrating an exemplary
sequence of steps for determining transmission characteristics for
a mobile radio transmitter.
[0035] FIG. 8: shows a flow diagram illustrating an exemplary
sequence of steps for determining location information for a mobile
radio transmitter.
[0036] FIG. 9: shows a diagram illustrating the determination of
the directional or angular location of a mobile radio transmitter,
with respect to an antenna system having three antennas arranged in
an equilateral triangle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] In FIG. 1, reference numeral 10 refers to a positioning
system for determining location information for a mobile radio
transmitter 1. Specifically, the positioning system 10 is
configured to determine location information indicating the
location of the mobile radio transmitter 1, e.g. within a space 6
of a local area extending up to 100-400 meters in any direction,
with a precision that enables discerning mobile radio transmitters
1 that are located in close proximity to each other within an area
of 1-2 square meters.
[0038] The mobile radio transmitter 1 is configured to generate a
radio signal 7 enabling communication in a local area with a range
of 1-200 meters (or more). Depending on the embodiment, the mobile
radio transmitter 1 comprises a WLAN-module (Wireless Local Area
Network), a Bluetooth transceiver, a Zigbee transceiver, and/or
another radio-based communication module providing an RSSI value
(Received Signal Strength Indicator). As illustrated schematically
in FIG. 1, the mobile radio transmitter 1 is arranged in an
electronic device 100, such as a radio dongle, a mobile radio
phone, a cellular phone, a smart phone, a wrist-worn device, a
smart watch, a tablet computer, a laptop computer, or the like.
[0039] As illustrated in FIG. 1, the positioning system 10
comprises an antenna system 2, including a plurality of antennas
21, a receiver system 3 which is electrically connected to the
antenna system 2 and configured to receive via each of the antennas
21 a radio signal transmitted by the mobile radio transmitter 1.
The positioning system 10 further comprises a processing circuit 4
electrically connected to the receiver system 3 and configured to
calculate the location information for the mobile radio transmitter
1 based on the radio signal received at each of the antennas 21, as
will be explained later in more detail. The processing circuit 4
comprises an application specific circuit (ASIC), a programmed
(micro-)processor, or another electronic circuit connected to a
data store 5 and configured to calculate the location information
of or for the mobile radio transmitter 1, respectively.
[0040] As illustrated in FIG. 2, the location information includes
the angular direction .PHI. of the mobile radio transmitter 1 with
respect to the antenna system 2. In some embodiments, the location
information further includes the distance D of the mobile radio
transmitter 1 from the antenna system 2. As one skilled in the art
will understand, from the relative location information, indicating
the angular direction .PHI. and distance D of the mobile radio
transmitter 1 with respect to the antenna system 2, an absolute
location of the mobile radio transmitter 1 can be determined, using
the (known) location of the antenna system 2.
[0041] As illustrated in FIGS. 1 and 3-6, the plurality of antennas
21 of the antenna system 2 are arranged on and fixed to a common
antenna carrier 20. The antennas 21 are implemented as patch
antennas or other antennas with spatial directivity. As illustrated
in FIGS. 3-6, the antennas 21 of the antenna system 2 are aimed at
different directions v1, v2, v3, v4, v5, v6, v7, v8.
[0042] FIG. 3 illustrates an embodiment an antenna system 2 which
enables two-dimensional (2D) positioning of the mobile radio
transmitter 1, using an arrangement of antennas 21 aimed at
different directions where the axes of direction v1, v2, v3 run in
a common plane (the drawing plane). One skilled in the art will
understand that 2D positioning is possible with three and more
antennas in various geometric arrangements, as long as their axes
of direction v1, v2, v3 run in one common plane. The specific
embodiment shown in FIG. 3 uses a triangular arrangement of the
antennas 21, i.e. they are arranged on a triangular antenna carrier
20 and/or their axes of direction v1, v2, v3 run parallel to the
sides of a triangle.
[0043] FIG. 4 illustrates an embodiment an antenna system 2 which
enables three-dimensional (3D) positioning of the mobile radio
transmitter 1, using an arrangement of antennas 21 aimed at
different directions where the axes of direction v4, v5, v6 do not
run in one common plane. One skilled in the art will understand
that 3D positioning is possible with four and more antennas in
various geometric arrangements, e.g. pyramidal, tetrahedral, or in
the shape of another polyhedron forming a quasi-spherical shape, as
long as their axes of direction v4, v5, v6 do not all run in a
common plane.
[0044] FIGS. 5 and 6 illustrate the receiver system 3 of the
positioning system 10 connected to an antenna system 2 comprising
two antennas 21 attached to an antenna carrier 20 in anti-parallel
configuration, their axes of direction v7, v8 pointing in opposite
directions. In the configuration of FIG. 5, the two antennas 21
have their own separate ground (backing) GND; in the configuration
of FIG. 6, the two antennas 21 share one common ground (plate) GND.
The two antennas 21 of the antenna system 2 of FIGS. 5 and 6 enable
one-dimensional (1D) directional positioning; they make it possible
to determine whether the mobile radio transmitter 1 is located in
front or behind a reference line or a reference plane r running
normal to the axes of direction v7, v8. In a further embodiment,
the antenna system 2 comprises two antennas 21 in parallel
configuration, i.e. their axes of direction run parallel to each
other and point in the same direction (the two parallel antennas 21
are thus aimed at different "targets" and therefore still
considered at being aimed at different directions). Finally in a
further embodiment, the two antennas 21 are at angular
configuration, their axes of direction running at an angle to each
other.
[0045] In the following paragraphs, described with reference to
FIG. 6 are possible sequences of steps for determining transmission
characteristics for the mobile radio transmitter 1. The
transmission characteristics of a mobile radio transmitter 1 are
determined during a calibration phase, e.g. by a user or a
manufacturer.
[0046] In step S1, the mobile radio transmitter 1 determines its
spatial orientation. Specifically, a processor of the mobile radio
transmitter 1 uses gyro-sensors to determine the spatial
orientation of the mobile radio transmitter 1. The spatial
orientation defines the cardanic position of the mobile radio
transmitter 1. Depending on the embodiment, the mobile radio
transmitter 1 comprises one or more further sensors, e.g. a
G-Sensor, an electronic compass, an acceleration sensor, and/or a
rotation sensor. The G-Sensor produces information about the
spatial orientation of the mobile radio transmitter 1 itself. Using
the information of the G-Sensor, the actual antenna gain is
calculated from recorded transmission characteristics. The
electronic compass is used to determine the relative transmission
orientation of the mobile radio transmitter 1. Typically, the
initial orientation of the mobile radio transmitter 1 with respect
to the antenna system 2 is not known. Owing to the Earth's magnetic
field there is a far-point common reference. In an embodiment, the
antenna system 2 comprises a magnetic field sensor to obtain this
reference information. Otherwise, without a magnetic field sensor,
the antenna system 2 must be aligned with respect to (true)
magnetic north. While the transmission characteristics of the
mobile radio transmitter 1 are recorded, the information of the
acceleration sensor(s) are integrated to detect minor position
shifts. The resulting change of the path loss is, thus, compensated
during recording. The data is further used for compensating minor
shifts of the mobile radio transmitter 1. Rotation sensors and/or G
Sensors are used to assist the user during the recording of
transmission characteristics of the mobile radio transmitter 1.
[0047] In step S2, the mobile radio transmitter 1 transmits its
spatial orientation wirelessly to the positioning system 10. The
spatial orientation of the mobile radio transmitter 1 is received
by the receiver system 3 via the antennas 21 of the antenna system
2. The processing circuit 4 of the positioning system 10 records
the signal strength of the radio signals received at each of the
antennas 21 (determined from received signal strengths indicator
RSSI or through measurement) and stores the respective signal
strengths in the data store 5 assigned to the received spatial
orientation. Remaining essentially in the same location, in step
S4, the spatial orientation of the mobile radio transmitter 1 is
changed by the user and steps S1, S2, and S3 are repeated to
determine, transfer, and store the various spatial orientations of
the mobile radio transmitter 1 and the respective signal strengths
obtained at each of the antennas 21 of the antenna system 2. For
example, the user is directed and guided by an app running on a
processor of the mobile radio transmitter 1. The app displays for
the user a visual feedback (e.g. based on information from the
rotation sensor and/or G-Sensors mentioned above), assisting the
user in determining which spatial orientation has been set and
transferred and which spatial orientation is still to be set and
transferred.
[0048] In step S5, from the stored spatial orientations and
recorded signal strengths, the processing circuit 4 of the
positioning system 10 generates the transmission characteristics
for the mobile radio transmitter 1. The transmission
characteristics of the mobile radio transmitter 1 indicates the
influence of the spatial orientation of the mobile radio
transmitter 1 on the signal strength received at the antenna system
2. The transmission characteristics are stored assigned to a device
identifier or a device type indicator of the mobile radio
transmitter 1.
[0049] In the following paragraphs, described with reference to
FIG. 7 are possible sequences of steps for determining location
information for the mobile radio transmitter 1.
[0050] In step S6, a radio signal 7 is received by the receiver
system 3 of the positioning system 10 from the mobile radio
transmitter 1 via all the antennas 21 of the antenna system 2.
[0051] In step S7, the receiver system 3 or the processing circuit
4, respectively, determines the characteristics of the radio
signals received at each of the antennas 21.
[0052] In one embodiment, the characteristics of the radio signals
include the propagation times of the radio signals at each of the
antennas 21. Accordingly, in step S72, the processing circuit 4
determines the propagation times of the radio signals received at
each of the antennas 21 (e.g. based on time values included at
transmission time by the mobile radio transmitter). Subsequently,
in step S9, the processing circuit 4 calculates the location of the
mobile radio transmitter 1 (based on or including its angular
direction .PHI. and distance D with respect to the antenna system
2) from the propagation times of the radio signals at each of the
antennas 21, using trigonometric functions.
[0053] In another embodiment, the characteristics of the radio
signals include the frequency shift of the received radio signals.
Accordingly, in step S73, the processing circuit 4 determines the
frequency shift of at least one of the radio signals received at
each of the antennas 21. Subsequently, in step S9, the processing
circuit 4 determines from the frequency shift a direction of
movement of the mobile radio transmitter 1, particularly, whether
the mobile radio transmitter 1 moves towards or away from the
antenna system 2.
[0054] In a further embodiment, the characteristics of the radio
signals include the signals strengths of the radio signals at each
of the antennas 21. Accordingly, in step S71, the processing
circuit 4 determines the signal strengths of the radio signals
received at each of the antennas 21. Subsequently, in step S9, the
processing circuit 4 calculates the directional location, i.e. the
angular direction .PHI. of the mobile radio transmitter 1 with
respect to the antenna system 2, from the signal strengths of the
radio signals received at each of the antennas 21, e.g. using
trigonometric functions.
[0055] An embodiment of calculating the directional location of the
mobile radio transmitter 1 is described below, with reference to
FIG. 9 which illustrates a scenario/configuration of an antenna
system 2 comprising three antennas 21a, 21b, 21c in an equilateral
triangle arrangement.
[0056] The behaviour of an antenna 21, 21a, 21b, 21c of the antenna
system 2, i.e. the antenna characteristics of the antenna 21, 21a,
21b, 21c of the antenna system 2, is specified and described by an
antenna function: gain=F(.alpha.) and its inverse function
.alpha.=F.sup.-1(gain). In essence, the behaviour or
characteristics of an antenna 21, 21a, 21b, 21c is specified by a
so called antenna diagram in polar coordinates which shows the
antenna gain in relation to the angular position of the mobile
radio transmitter 1 with respect to the antenna 21, 21a, 21b, 21c.
For the antenna function, gain=F(.alpha.), the polar antenna
diagram is transformed into a Cartesian diagram with gain as a
function of angular position, .alpha.=[0.degree. . . .
180.degree.], also considering forward and backward gain.
[0057] In a first step, for calculating the directional location of
the mobile radio transmitter 1, the processing circuit 4 determines
a sector S in which the mobile radio transmitter 1 is located in
relation to the antenna system 2, using minimum and/or maximum
received signal strengths at each antenna 21a, 21b, 21c, as
illustrated in FIG. 9.
[0058] In a subsequent step, the processing circuit 4 calculates
the location of the mobile radio transmitter 1 inside this sector S
based on the received signal strength, using trigonometry and angle
calculation and considering the antenna function F. The signal
received at antenna 21a is RSSI1=F(.alpha.1). The angle .alpha.1 is
calculated using the inverse function .alpha.1=F.sup.-1(RSSI1).
Likewise for antenna 21b the angle .alpha.2 is calculated using the
inverse function .alpha.2=F.sup.-1(RSSI2).
[0059] In case of a distant mobile radio transmitter 1, the angle
.gamma. is very small, converging to 0.degree.. One skilled in the
art will see that .alpha.2=.alpha.1-120.degree. and can use both
.alpha.1 and .alpha.2 for the angular position.
[0060] In a further step, the processing circuit 4 calculates the
distance of the mobile radio transmitter 1 from the antenna system
2 based on the path loss. The most relevant parameters of the link
budget (e.g. transmitter power, antenna characteristics etc.) are
known. One skilled in the art can calculate the distance from the
path loss by using existing propagation models.
[0061] Calculating distance based on received signal strength
produces significant deviations when obstacles (e.g. walls) are
involved. In such cases, measuring propagation times enables more
precise distance calculation.
[0062] In a further embodiment where the characteristics of the
radio signals include the signal strengths of the radio signals at
each of the antennas 21, in step S8, the processing circuit 4
determines the transmission characteristics for the respective
mobile radio transmitter 1, e.g. by determining the transmission
characteristics assigned to the particular mobile radio transmitter
1 or the respective device type of the particular mobile radio
transmitter 1, as stored in data store 5 of the positioning system
10 or retrieved from a remote server. Subsequently, in step S9, the
processing circuit 4 calculates the location of the mobile radio
transmitter 1, including the distance D of the mobile radio
transmitter 1 from the antenna system 2 in addition to the angular
direction .PHI. with respect to the antenna system 2. The distance
D is calculated by the processing circuit 4 from the signal
strengths of the radio signals received at each of the antennas 21,
using the transmission characteristics and an indication of the
current spatial orientation of the mobile radio transmitter 1,
included in the radio signal 7. Specifically, from the obtained
transmission characteristics, the processing circuit 4 determines
the corresponding attenuation of the radio signal 7 detected at the
antenna system 2, if any, at the current spatial orientation of the
mobile radio transmitter 1. One skilled in the art will understand
that in addition to the transmission characteristics and the
spatial orientation of the mobile radio transmitter 1, calculation
of the distance further depends on the reception characteristics
and configuration of the antenna system 2 and its antennas 21. The
reception characteristics and configuration are determined during a
calibration phase at manufacturing time and stored in data store
5.
[0063] In optional step S10, the positioning system 10 transmits
the location information to the mobile radio transmitter 1.
[0064] For local adjustment, the mobile radio transmitter 1
performs fine tuning during recording of the transmission
characteristics of the mobile radio transmitter 1 to enhance
precision that would otherwise be reduced by positional shifts of
the mobile radio transmitter 1. Furthermore, the mobile radio
transmitter 1 performs local adjustments or fine tuning of the
location information received from the antenna system 2, by
considering/compensating positional shifts detected by the sensors
of the mobile radio transmitters 1, to improve system accuracy.
[0065] In optional step S11, the processing circuit 4 of the
positioning system 10 determines a movement path, movement
direction, and/or movement speed of the mobile radio transmitter 1
from a plurality of consecutively calculated locations of the
mobile radio transmitter 1. For example, in a scenario where the
positioning system 10 is arranged at an access control device, such
as gate or a door, the positioning system 10 is configured to
determine whether the mobile radio transmitter 1, and thus its
user, is approaching or moving away from the access control device.
As indicated schematically in FIG. 8, in an embodiment, in step
S12, the processing circuit 4 uses the movement path of the mobile
radio transmitter 1 to predict and/or calculate the location
information for the mobile radio transmitter 1.
[0066] It should be noted that, in the description, the sequence of
the steps has been presented in a specific order, one skilled in
the art will understand, however, that the order of at least some
of the steps could be altered, without deviating from the scope of
the invention.
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